Hi David, <snip>
> > Well, if you NAT the destination identifier into a routing locator > when a packet traverses the source edge/core boundary and NAT the > locator back into the original destination identifier when you get to > the core/destination edge boundary, it might be relevant. The > advantages I see of such an approach would be: > > - no need to modify existing IPv6 stacks in any way > - identifiers do not need to be assigned according to network > topology (they could, in fact, be allocated according to national > political boundaries, geographic boundaries, or randomly for that > matter). They wouldn't even necessarily have to be IPv6 addresses > just so long as they could be mapped and unmapped into the > appropriate locators (e.g., they could even be, oh say, IPv4 addresses). > - locators could change arbitrarily without affecting end-to-end > sessions in any way > - the core/destination edge NAT could have arbitrarily many locators > associated with it > - the source edge/core NAT could determine which of the locators > associated with a destination it wanted to use > > Of course, the locator/identifier mapping is where things might get a > bit complicated. What would be needed would be a globally > distributed lookup technology that could take in an identifier and > return one or more locators. It would have to be very fast since the > mapping would be occurring for every packet, implying a need for > caching and some mechanism to insure cache coherency, perhaps > something as simple as a cache entry time to live if you make the > assumption that the mappings either don't change very frequently and/ > or stale mappings could be dealt with. You'd also probably want some > way to verify that the mappings weren't mucked with by miscreants. > This sounds strangely familiar... > Certainly does. Apparently this or a similar idea was suggested back in 1997, and is the root origin of the 64 bits for host address space, according to Christian Huitema, in his IPv6 book - http://www.huitema.net/ipv6.asp. A google search found the draft : "GSE - An Alternate Addressing Architecture for IPv6" M. O'Dell, INTERNET DRAFT, 1997 http://www.caida.org/outreach/bib/networking/entries/odell97GSE.xml > > Can two evils make a good? :-) > Not sure, however, two wrongs don't make a right, but three lefts do. Regards, Mark. -- The Internet's nature is peer to peer.